1. Field of the Invention
The present invention relates generally to a system and method for evaluation of integrated circuits and other semiconductor devices. More particularly, it relates a system incorporating hardware and suitable interconnections which allow efficient burn-in testing of a multiplicity of semiconductor devices while still incorporated in a semiconductor wafer. This invention is related to the inventions in commonly owned U.S. Pat. No. 5,429,510, issued to Barraclough et al. on Jul. 5, 1995, entitled xe2x80x9cHigh-Density Interconnect Technique,xe2x80x9d and commonly owned U.S. Pat. No. 5,682,472, issued to Brehm et al. on Oct. 28, 1997 and entitled xe2x80x9cMethod and System for Testing Memory Programming Devices,xe2x80x9d the disclosures of which are hereby incorporated by reference herein. This invention is further related to the invention in a concurrently filed, copending, commonly owned application filed in the names of Frank O. Uher, Mark C. Carbone, John W. Andberg and Donald P. Richmond II, entitled xe2x80x9cWafer Level Burn-In and Test Cartridgexe2x80x9d Ser. No. 09/353,214, the disclosure of which is also incorporated by reference herein.
2. Description of the Prior Art
When fabrication of integrated circuits and other semiconductor devices has been completed, the semiconductor devices are subjected to burn-in and electrical tests in order to identify and eliminate defective semiconductor devices before shipment to a customer. The term xe2x80x9cburn-inxe2x80x9d relates to operation of an integrated circuit at a predetermined temperature or temperature profile, typically an elevated temperature in an oven, a reduced temperature in an environmentally controlled enclosure, or a combination of an elevated temperature followed by a reduced temperature. Certain operating electrical bias levels and/or signals are supplied to the semiconductor devices while they are at the elevated temperature. The use of the elevated temperature or the combination of an elevated temperature followed by a reduced temperature accelerates stress to which the devices are subjected during burn-in, so that marginal devices that would otherwise fail shortly after being placed in service fail during burn-in and are eliminated before shipping. In electrical test, a more complete set of operating electrical bias levels and signals are supplied to the device to provide a thorough evaluation of its functions.
As is apparent from the Brehm et al. patent, there are a variety of burn in and electrical test systems known in the art for burn-in and electrical test of integrated circuits and other semiconductor devices. To date, most of the prior art systems carry out the burn-in and electrical test after the integrated circuits have been separated into individual chips or die from a wafer in which they have been manufactured.
More recently, interest has developed in wafer-level burn-in systems, some of which systems also include electrical test capability. In these systems, the integrated circuits undergo burn-in and may undergo electrical test prior to separation into individual integrated circuit chips.
Wafer-level burn-in systems have attracted interest because they allow defective integrated circuits to be identified by the burn-in process before additional expense is incurred in their handling and packaging. Similarly, it is desirable to carry out electrical test of the integrated circuits while they are still in wafer form. Electrical test involves applying a suite of electrical signal inputs to each integrated circuit to make sure that it performs properly for its intended use.
While the ability to carry out both burn-in and electrical test in a single wafer-level system is a highly desired result, there are significant interconnection, signal supply and power supply problems to be overcome before such a system can be implemented in practice. In a preferred implementation, the present invention is directed to solving those problems. In its broadest form, aspects of the present invention may, however, be employed in a system that carries out wafer-level burn-in or wafer-level electrical test alone.
In accordance with one aspect of the invention, a burn-in test system includes a device under test zone configured to receive a plurality of cartridges each containing a semiconductor wafer including a plurality of integrated circuits. Each of the plurality of cartridges includes a rigid probe signal printed circuit board and a probe power printed circuit board substantially parallel to and closely spaced from the rigid probe printed circuit board. Test electronics are positioned adjacent to the device under test zone. Power electronics are positioned adjacent to said device under test zone. A first interconnection system connects the test electronics to the rigid probe signal printed circuit board. A second interconnection system connects the power electronics to the probe power printed circuit board. The first and second interconnection systems are arranged in a stacked relationship. The probe power printed circuit board has at least a bendable section permitting a portion of the probe power printed circuit board to be spaced a greater distance away from the rigid probe signal printed circuit board proximate to the second interconnection system.
In accordance with a second aspect of the invention, a test system includes a device under test zone configured to receive a plurality of cartridges each containing a semiconductor wafer including a plurality of integrated circuits. Each of the plurality of cartridges includes a rigid probe signal printed circuit board and a probe power printed circuit board substantially parallel to and closely spaced from the rigid probe printed circuit board. Test electronics are positioned adjacent to said device under test zone. Power electronics are positioned adjacent to the device under test zone. A first interconnection system connects the test electronics to the rigid probe signal printed circuit board. A second interconnection system connects the power electronics to the probe power printed circuit board. The first and second interconnection systems are arranged in a stacked relationship. The probe power printed circuit board has at least a bendable section permitting a portion of the probe power printed circuit board to be spaced a greater distance away from the rigid probe signal printed circuit board proximate to the second interconnection system.
In a third aspect of the invention, a burn-in system has a temperature controlled zone configured to receive a plurality of cartridges each containing a semiconductor wafer including a plurality of integrated circuits. Test electronics are positioned in a cool zone. Power electronics are positioned in the cool zone. A transition zone separates the temperature controlled zone and the cool zone.
In a fourth aspect of the invention, a test system includes a device under test zone configured to receive a plurality of cartridges each containing a semiconductor wafer including a plurality of integrated circuits. Test electronics on a first circuit board are positioned adjacent to the device under test zone. Power electronics on a second circuit board are positioned adjacent to said device under test zone. Each of the plurality of cartridges are connected to the test electronics by a first connection between one of the plurality of cartridges and the first circuit board and to the power electronics by a second connection between the one of said plurality of cartridges and the second circuit board separate from the first connection.
In a fifth aspect of the invention, a test system includes a first plurality of test channels each adapted to receive a second plurality of integrated circuits under test. A second plurality of power modules are each connected to one of the integrated circuits under test in each test channel. A controller is connected and configured for successive selection of one of the first plurality of test channels.
In a sixth aspect of the invention, a method for burn-in testing integrated circuits in wafer form includes providing a temperature controlled zone configured to receive a plurality of cartridges each containing a semiconductor wafer including a plurality of integrated circuits. The integrated circuits are tested with test electronics positioned in a cool zone. Power is provided to the integrated circuits with power electronics positioned in the cool zone. The test and power electronics are separated from the temperature controlled zone with a transition zone between the temperature controlled zone and the cool zone.
In a seventh aspect of the invention, a method for testing integrated circuits in wafer form includes connecting a first plurality of integrated circuits in a second plurality of test channels. A first plurality of power modules is connected to one of the integrated circuits under test in each test channel. One of the second plurality of test channels is selectively selected. The first plurality of the integrated circuits in the selected test channel is tested. The selective selection and testing steps are repeated until all of the integrated circuits have been tested.
In reviewing the following more detailed description and drawings of the present invention, the advantages and features of the invention should be more readily apparent to those skilled in the art.